Contribution of limbs’ actions to the four competitive swimming strokes: a nonlinear approach

The aim of our study was to assess the effect of the limbs’ actions on the nonlinear properties of the four competitive swimming strokes. Forty-nine swimmers performed all-out sprints at front-crawl, backstroke, breaststroke and butterfly, each one at full stroke (FS), only the arms’ stroke (AS), and only leg kicking (LK), in a total of 12 bouts, 6 per day. A speedo-meter cable was attached to the swimmer’s hip, to collect the speed-time raw data (f = 50Hz). Velocity, speed fluctuation, sample entropy and fractal dimension were derived from the speed-time series. Significant and moderate-strong effects were noted for both stroke and condition in all variables in the study (p ≤ 0.001; 0,560<η² < 0,952). The four competitive strokes and their three conditions exhibited nonlinear properties. The swimming pattern was less complex and more predictable for LK in comparison to AS and FS. Breaststroke and butterfly have more complex but more predictable patterns than backstroke and front-crawl.     

贵州城市体系空间结构与分形特征研究

在定性描述贵州城市体系空间结构特征的基础上,运用分形理论对贵州城市体系空间结构进行了定量研究.结果表明贵州各城市在空间分布上有分形特点,基本呈分散分布.城市之间运输网络通达能力较低,结构还不完善且规模小,与现代城市经济发展的要求差距较大,并指出了贵州交通运输网发展滞后的原因和优化空间结构的思路.     

李白生卒年之再考察

李白之生卒年,自清人王琦之后,今世之李白研究界又提出了一些新的说法.本文以对李白<为宋中丞自荐表>、<为宋中丞请都金陵表>作年的考辨为基础,确认李白生于长安元年(701),卒于宝应元年(762),以明它说之不实.     

数据挖掘技术在计算机入侵检测中的应用

分析了聚类、分类、关联规则等在IDS中常用的数据挖掘算法,并介绍了DAID这种以数据库为中心的数据挖掘体系架构模型,对其数据处理过程进行展现。     

枣文化旅游开发研究

随着旅游业的发展,传统意义上的观光旅游已不能满足旅游者的需要,深度挖掘果品文化内涵,并应用于旅游产品开发,是目前观光果园开发研究的重要课题。本文在归纳枣文化内涵基础上,总结我国枣文化旅游现状及存在问题,提出枣文化旅游开发对策,结合乐陵国强百枣园提出具体开发构想。     

设备混合布局问题研究

针对目前设备混合布局问题存在布局形式表达、建模与求解等一系列难题,将设备混合布局问题转化为多单元布局问题,通过求解单元布局问题间接求解设备混合布局问题.实例表明,该方法不限设备混合布局的形式,无须建模和设计算法,可较好地解决设备混合布局问题,为相关研究提供理论参考.     

Evidence of the relative age effect in football in Australia

Abstract

The birth date distributions of elite male and female footballers in Australia, from junior youth (age 14 and upwards) to senior (professional) players, were examined. A statistically significant relative age effect was found among junior male players, reducing in effect with increasing age. An inter-year relative age effect that became apparent among the players at national level in the Under-17 and Under-20 age groups, due to the timing of the respective World Cups for those age groups, was also identified. It is conjectured that this might lead to players born in certain years having a curtailed pathway in the elite game, leading to drop-out among this very elite group. In the case of women elite players, no significant relative age effect was found among youth players, possibly due to less fierce competition for places, although a significant effect was found to exist at senior elite level.     

分形理论在土地利用类型研究中的应用

以济南市历城区孙村镇为例，运用分形理论对土地利用类型的分布是否具有分形结构进行了分析．结果表明：孙村镇各土地类型的分布具有分形结构，其中独立工矿用地、农村居民点、水浇地、果园、城镇建设用地、荒草地的分维值偏离随机运动值（1．500）较大，说明这6种土地利用类型处于一种相对稳定的状态，比较接近规则体；而交通用地、旱地偏离随机运动值较小，说明这2种土地利用类型受该区域自然地理条件的影响；交通用地、旱地的布局较复杂且不稳定．这一结论为定量地量度土地利用是否合理、科学找到了一个全新的定量化指标或参考参数．     

品种、播种期和密度对春大白菜产量的影响

品种、播种期和密度中对春大白菜产量影响最大的是品种,其次为密度,播种期影响最小.三因子的最佳组合方案为:品种,北京小杂55;播种期3月27日,密度5333株/亩.     

求证现代教育方程的约定解——试论复杂性理论的教育学应用

现代教育系统是一个开放的复杂巨系统,更为重要的是,它内在地容涵于特殊复杂巨系统———社会系统之中。现代教育系统愈来愈呈现出非线性、复杂性、自组织性(涌现)、分形与分岔等特质。复杂性理论不仅对现代教育具有方法论和认识论意义,同时具有对现代教育的本体论解释功能。建立中国特色的“教育集成研讨厅,发挥人与人、人与物的多重因素的效果,综合地解决现代教育的种种问题,并对教育理论与复杂性理论的关系进行理性反思,可以使我们在辩证法的层面上,达到武器的批判和批判的武器二者的对立统一。